Hitherto, various such apparatuses have been suggested. For example, machines for forming a continuous seamless concrete background pipe are known from U.S. Pat. Nos. 3,785,759 and 3,877,860. Tunneling machines which both excavate and form a concrete tunnel wall are also known from U.S. Pat. Nos. 3,350,889 and 3,561,223, for example. Sometimes, the tunneling machine of the prior art discharges spoil including a vast quantity of water, therefore it is very difficult to find the place for easily discharging the spoil mixed with the water. If the water can be separated from the spoil, it is very easy to discharge the water anywhere without problems. The aboveground concrete pipe and the tunnel wall constructed using the machines of prior art are made of concrete, therefore the strengths thereof are low.